Spatial and surround sound audio recording is becoming a more common feature of video recorders and other audio recording devices. Spatial and surround sound audio recording may be performed in various manners, including with discrete multichannel techniques, such as 5.1 and 7.1 surround sound, soundfield-based Ambisonics, as well as techniques that separate the spatial information at least partially from the audio signals. Among those techniques that separate the spatial information at least partially from the audio signals are spatial audio capture (SPAC) and directional audio coding (DirAC).
Regarding these techniques for spatial and surround recording, discrete multi-channel techniques map the transmitted audio channels to fixed loudspeaker positions. As such, modifications, such as rotations, to the soundfield may be cumbersome. The Ambisonics technique records the spatial derivatives, at least to a given order, of the soundfield at one point and enables decoding to varying transducer layouts at reproduction. The Ambisonics technique allows some spatial modifications, such as rotation utilizing matrix multiplication. SPAC and DirAC techniques are based on transmitting one or more audio channels and an associated stream of spatial parameters for multiple frequency bands. The spatial parameters include at least the direction of arrival of the audio signals, but may also include other parameters, such as diffuseness. Like the Ambisonics technique, SPAC and DirAC techniques require decoding for the reproduction transducer set up and may support an arbitrary loudspeaker set up and reproduction over headphones. The SPAC and DirAC techniques also enable spatial modifications by modification of the stream of spatial information. For example, soundfield rotation may be implemented by changing the angles of arrival and the spatial parameters. Further details regarding SPAC techniques are provided by U.S. Patent Application Publication No. US 2012/0128174 and by U.S. Patent Application Publication No. US 2013/0044884, the contents of both of which are incorporated herein in their entirety.
The audio signals captured by spatial and surround sound recording may suffer from disturbances caused by noise, such as mechanical and electrical noise. In regards to video recorders, for example, noise created by the auto-focus and zoom motor may disturb the audio signals. As another example, handheld audio recording devices may correspondingly suffer from handling noise.